Lyophilized, LOT, EXP, USP, single-dose versus multiple-dose: what each term on a vial label means and which one sets your math.
Key points
- 01Lyophilized: freeze-dried, not concentrated. Lyophilization removes water under vacuum and leaves a dry cake or a thin film at the bottom of the vial. The word tells you the contents are stable dry and that a diluent has to be added before anything can be measured, which is what our reconstitution guide walks through.
- 02The milligram figure is contents, not a dose. A label reading 5 mg states the mass sealed in the vial. It becomes a concentration only when you record the diluent volume you added, and it becomes a dose only when a prescriber or, in a research context, the compound's handling documentation says so.
- 03Single-dose versus multiple-dose container. These are defined terms rather than marketing. In the standard usage a single-dose container has no antimicrobial preservative and is intended for one entry, while a multiple-dose container is formulated for repeat entry within a limited period after the first puncture.
- 04LOT and EXP do different jobs. The lot number identifies the production batch and is the number a recall or a complaint is filed against, so it belongs in your log. The expiry date applies to the sealed vial stored as the label directs, and it stops governing once you have added diluent.
- 05USP on a diluent label is a specification. Bacteriostatic Water for Injection USP means the product is made to a published monograph, including the preservative content. It is a statement about what is in the bottle, not a statement about what the bottle may be mixed with.
- 06Excipients and research-use wording. Names like mannitol or an acetate buffer are excipients that protect the peptide during drying and storage; they are not the active mass. Wording such as for research use only, not for human use, is a statement about how the material was supplied and tested, and this site treats it as binding.
Frequently asked questions
What does lyophilized mean on a vial?+
Freeze-dried. Water was removed under vacuum, leaving a dry cake or film that is stable in storage and has to be reconstituted with a diluent before any dose can be measured. Educational information only, not medical advice.
Is the milligram number on the label my dose?+
No. It is the total mass sealed in the vial. Divided by the diluent volume you add, it gives the concentration; the dose itself comes from your prescriber or, for a research compound, from the handling documentation.
What is the difference between a single-dose and a multiple-dose vial?+
Preservative and intended entries. A single-dose container is unpreserved and intended for one puncture; a multiple-dose container is formulated for repeat entry over a limited period after the first one.
Why should I record the lot number?+
Because it identifies the batch. If a recall is issued or you need to report a problem with the product, the lot number is what the report is filed against, and it is easy to lose once the carton is discarded.